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Date: Fri, 11 Jan 2013 10:38:27 +0100
From: magnum <>
Subject: Re: New plugin load order magic

On 11 Jan, 2013, at 10:26 , Frank Dittrich <> wrote:
> On 01/11/2013 09:27 AM, magnum wrote:
>> On 11 Jan, 2013, at 8:58 , Solar Designer <> wrote:
>>> On Fri, Jan 11, 2013 at 08:26:40AM +0100, magnum wrote:
>>>> I was just considering reverting my patch for now.
>>> Yes, I think you should.
>> I reverted it now but we need to fix this somehow. For the horribly slow iterated formats that are getting common now, we just can't default to CPU formats on a GPU build.
> There might be a solution if we extend the format interface in the future.
> A format could then specify a fallback format which is used for --show.
> This would, however, create dependencies between formats. Then, users
> cannot just remove the CPU implementation of a plugin format.
> And if those "horribly slow iterated formats" have GPU implementations
> with extremely high MAX_KEYS_PER_CRYPT values, it is not always a good
> idea to default to GPU implementations.
> Imagine a user who is not aware of the impact of MAX_KEYS_PER_CRYPT:
> He could well be launching more than 20 different attacks (small word
> lists, few rules) with a *total* number of password candidates still
> smaller than MAX_KEYS_PER_CRYPT.
> (May be we even need another fallback format for --single mode.)

True. We have reduced this problem a lot by setting MIN_KEYS_PER_CRYPT to local work size for a number of formats now, but CPU formats are often better for short runs regardless of that.

To add even more confusion to the mix, I think we should ideally separate format from implementation. So you would always say --format=raw-md5 for raw md5 hashes, and then add (or default to) some other option for making use of OpenCL or CUDA if available.

The idea of fallback formats might be worth giving more thought.


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